Final answer:
The best oral antimicrobial option for treating community-acquired methicillin S. aureus cutaneous infection is trimethoprim-sulfamethoxazole (TMP/SMZ), especially before the results of an antimicrobial susceptibility test are available.
Step-by-step explanation:
The oral antimicrobial option for the treatment of community-acquired methicillin S. aureus cutaneous infection would be trimethoprim-sulfamethoxazole (TMP/SMZ). Other antibiotics like amoxicillin, dicloxicillin, and cephalexin are usually less effective against MRSA (Methicillin-Resistant Staphylococcus aureus). Prior to antimicrobial susceptibility testing, infections thought to be caused by S. aureus, particularly MRSA, are frequently treated with medications known to be efficacious against those strains, which includes TMP/SMZ, clindamycin, doxycycline, minocycline, or linezolid.
Once an antimicrobial susceptibility test (AST) is performed and the results show which antibiotics the bacteria is sensitive to, the treatment can be tailored more precisely. If S. aureus shows resistance to common antibiotics but is susceptible to certain drugs, those should be used. However, AST takes time, so initial treatment is often started with an antibiotic like TMP/SMZ to cover MRSA.